(1) Field of the Invention
The present invention relates to a low-cost drip-absorbing sheet for absorbing and separating drips generated from perishable foods, to prevent a lowering of the quality of the foods.
(2) Description of the Related Art
In perishable foods such as meat, fish, vegetables and fruits (hereinafter referred to as "foods"), when the cells thereof are destroyed, fluids inside and outside the cells flow out, resulting in a loss of freshness of the foods.
This loss of freshness causes a lowering of the water retention of foods and an increased quantity of an exudate, i.e., "drip", whereupon an autolysis of the foods, a propagation of bacteria, an oxidation of lipids, and a discoloration of the foods occur, and the lowering of the quality thereof is accelerated.
It is well-known in the food industry that, if the drips thus generated can be separated, this will effectively maintain the freshness of foods. Nevertheless if foods are stored in the state where drips generated from foods are absorbed in paper, sponge or the like, although it seems that the drips are separated from the foods, the foods are always in contact with the drips and the effect of maintaining the freshness thereof cannot be obtained.
On the other hand, if a part of water contained in foods is separated in advance, and the foods are stored in this state, the generation of drips is controlled and the freshness effectively maintained.
Also the method of storing foods while absorbing and separating drips exuding from the foods is effective.
As the food-preserving method, there has been long adopted a method in which foods are placed in direct contact with a water-absorbing substance, to remove water from the foods and improve the preservability thereof, but this method is defective in that the taste of the foods is changed.
With the development of water-absorbing polymers, as the means for reducing the water content in foods or removing generated drips without changing the taste of the foods, there have recently been proposed various water-removing sheets comprising a combination of a water-absorbing polymer and a semipermeable membrane (see, for example, Japanese Examined Utility Model Publication No. 58-43922, Japanese Examined Patent Publication No. 58-58124, Japanese Examined Utility Model Publication No. 61-3337, Japanese Examined Patent Publication No. 1-22816 and U.S. Pat. No. 4,383,376), and water-removing sheets comprising a semipermeable membrane and a liquid saccharide (see U.S. Pat. No. 4,819,342). These sheets are utilized for removing water from foods in advance, before storage, or for separating drips generated from foods during storage.
In these water-removing sheets, a granular polymeric water absorber or a liquid saccharide is used and enveloped so that one surface of the envelope is formed of a semipermeable membrane, and the periphery of the semipermeable membrane is bonded to effect a sealing thereof. Accordingly, the water-absorbing sheet of this type is advantageous in that the sheet can be used repeatedly, but a special technique or apparatus is necessary for the production and the number of steps is high and therefore, the manufacturing cost is increased.
Furthermore, since the sheet is marketed in the state where the periphery is bonded and sealed, variations of the sizes are limited and a user must select an appropriate size: often it is impossible to obtain a sheet having a desirable size.